Organize Your Life with Nepomuk

When you build a house, you cannot start with the paint, fancy windows
and doorbell. Instead, you spend a lot of time digging in
the ground, disturbing the neighbors and making little visible progress
while you lay the foundation. It has been much the same with Nepomuk,
the Semantic Desktop technology of the KDE platform. Work has been going
on for a long time beneath the surface, causing occasional
disruption—such as file indexing slowing down the rest of your
desktop—with
little visible progress. However, the foundations now are solid, the
main structures are in place, and KDE's developers are adding features
that make Nepomuk useful for you, right now.

So, what can Nepomuk actually do for you?

Stop Searching, Start Finding

The first thing Nepomuk offers is file searching integrated into
your KDE applications. If your distribution has enabled Nepomuk, files
also can be tagged and rated from KDE's Dolphin file manager. You can
search for files simply by typing a query into Dolphin's search box,
which brings up results and a panel of basic options that make it easy
to refine the search. These enable you to limit searching to the current
folder and let you choose whether to search everything, text documents
(including OpenDocument texts and PDFs), images or filenames. When you have
identified the files you want, you can use the Save button to add the
search query to your Places panel on the left of the Dolphin window,
making the search available in the future via a single click. The saved search
also is available in the file chooser dialog of all KDE applications.

Figure 1. You can access saved searches from the
Places sidebar.

What Is This Thing Called Nepomuk?

Nepomuk (also known as the Networked Environment for Personalized,
Ontology-based Management of Unified Knowledge) began as a research project
funded by the European Union to explore better ways of
managing, understanding and sharing desktop information. It attracted
participation from corporations, such as IBM and Linux vendor Mandriva, in
addition to
involvement from the National University of Ireland.

The initial project ran from 2006 to 2008, during which time a reference
implementation was written in Java. Mandriva and KDE have since worked
on integrating the ideas into KDE software, retaining the name Nepomuk.

Practical use of the technology required a high-performance file indexer
and query database. Initially, Nepomuk's own Java-based Sesame
query framework was used in the KDE implementation, but its reliance on Java
led to packaging problems for some distributions, and KDE switched
to Virtuoso in 2009. No longer held back by these technical constraints,
the main barriers to making greater use of Nepomuk in KDE software have
been removed.

You can access additional search options in Dolphin 1.5 (part of KDE
software compilation 4.5) by clicking the green + button. These provide
filtering based on file modification date, size, tags or rating. You can
continue to add and combine additional filters until you have isolated
the exact files you want—for example, by limiting the search to files
with a particular tag that have not been modified since a particular
date. You also can use the filters directly without any search terms.

Figure 2. Dolphin 1.5 lets you combine filters
to narrow your search.

When Nepomuk first came to KDE software, it lacked a good graphical
search interface to expose its capabilities. Nepomuk always has offered
the ability to construct complex search queries using a query language,
such as SPARQL. You could, and still can, enter queries in this way
using Dolphin. Click on the breadcrumbs above the search results to
access Dolphin's editable location bar, view the query that was used
to generate the results and edit it directly. However, many users do
not have an intimate knowledge of the query language constructs and
would consider such an approach better suited to the command line than a
graphical file manager. The search interface in Dolphin 1.5 graphically
exposed many of Nepomuk's search capabilities for the first time.

Peter Penz, Dolphin's lead developer, still sees problems with the search
interface in Dolphin 1.5: “It just takes way too many clicks to specify
a query.” KDE developers, including Peter and Mandriva's Sebastian
Trüg have been grappling with the problem of making a good graphical
interface that exposes the power of Nepomuk searches in a more convenient
manner. In 2009, Alessandro Sivieri began work on “faceted
browsing”,
an approach to the problem that provides panels of search filters in the
file manager sidebar, resulting in his Sembrowser prototype (see Resources).
Now,
these ideas have come together to provide a faceted browsing sidebar in
Dolphin 1.6 (part of KDE software compilation 4.6) that appears when
you start a search and makes additional filters available with single
clicks. Faceted browsing also will be integrated into the KDE platform,
making it available for other KDE applications to use.